Importance of enhanced mass resolution in removing interferences when measuring volatile organic compounds in human blood by using purge-and-trap gas chromatography/mass spectrometry

Abstract

The number of volatile organic compounds (VOCs) that can be purged from human blood is so great that they cannot be separated completely by capillary gas chromatography. As a result, the single-mass chromatograms used for quantitating the target compounds by mass spectrometry have many interferences at nominal (integer) mass resolution of a quadrupole mass spectrometer. The results of these interferences range from small errors in quantitation to completely erroneous results for the target VOCs. By using a magnetic sector mass spectrometer, these interferences at nominal mass can be removed at higher resolution by lowering the ion chromatogram windows around the masses of interest. At 3000 resolution (10% valley definition), unique single-ion chromatograms can be made for the quantitation ions of the target VOCs. Full-scan mass data are required to allow the identification of unknown compounds purged from the blood. By using isotope-dilution mass spectrometry, most target VOCs can be detected in the low parts per trillion range for a 10-mL quantity of blood from which the VOCs have been removed by a purge-and-trap method.

Analysis of Human Skin Emanations by Gas Chromatography/Mass Spectrometry. 2. Identification of Volatile Compounds That Are Candidate Attractants for the Yellow Fever Mosquito (Aedes aegypti)

“…(2) Reported previously as a volatile human effluent . (3) Reported previously as a volatile in human blood . (4) Reported previously as a component of fingerprint residue .…”

Determination of elemental compositions by gas chromatography/time‐of‐flight mass spectrometry using chemical and electron ionization

“…If better mass resolving power is required, e.g. for complex samples, magnetic sector instruments have long been in use for this purpose 9…”

Single-walled carbon nanotubes as an effective adsorbent in solid-phase microextraction of low level methyl tert-butyl ether, ethyl tert-butyl ether and methyl tert-amyl ether from human urine

“…Nevertheless, it has been noted that the use of a specific detectors such as FID or PID to detect MTBE in complex matrices can lead to mistakes and/or false positive results, whereas MS insures high specificity in the identification of the analytes. Several papers reporting the determination of MTBE and other ethers in human blood [7,13,14,[24][25][26][27][28][29][30][31][32][33], and urine [15][16][17][18][19]26,34,35] were also found. In its latest versions MTBE is sampled by headspace SPME and analyzed by GC-MS [27,29].…”